How did my Pokemon and Items storage increase without buying them?

Solution 1:

I really doubt you have a "cracked" version of the APK. The storage limits are certainly kept server side. No crack will change that.

Niantic has been having issue where people would login to find that their account has made progress since their last login. It's not clear if someone is stealing accounts for some reason, but it's likely a server issue that muddles your progress with someone else's.

Solution 2:

The only way to increase Pokemon and bag storage is through the store via Pokécoins from in-game purchases (or collecting them from your Defender bonus over the course of a few days or weeks).